Cathode-ray tube and process



Jan. 4, 1944. s. J. KocH CATHODE RAY TUBE AND PROCESS Filed Nov. 28, 1941 2 Sheets-Sheet 1 i ""ib Jan. 4, 1944. s, 1 KOCH 2,338,336

CATHODE RAY TUBE AND PROCESS Filed Nov. 28, 1941 2 Sheets-Sheet 2 H i Z4' V 21 l l l! 12 l 10] 35 `m/VENTOR.

,7 i' MW Patented Jan. 4, 1944 2,338,336 CATHOD-RAY TUBE AND PROCESS Stanley J. Koch. Clifton, N. J., assigner to Allen B. Du Mont Laboratories, Inc., Passaic', N. J.. a corporation of Delaware Application November 28, 1941, Serial No. 420,744

12 Claims.

'Ihis invention relates to a cathode-ray tube and the process of producing the same, in which the electrical gun assembly is attached to the conductors that pass through the glass before the sealing of the vglass assembly together. In one modiiication of the invention, glass beads are :first sealed to the conductors before the conductors are sealed in place. By this invention the conductors may be brought out in such a manner as to provide the highest insulation between the conductors because the conductors pass through the glass on a circle of maximum diameter. In obtaining this maximum diameter, steps are taken that are very suitable for the processing of glass, thus simplifying the manufacturing process.

In carrying out this invention the cathode-ray tube leads are made to extend through the glass and are sealed in such a manner as to provide a maximum of insulation between the lead wires. With this invention the lead wires can be brought out on a circle whose diameter is almost as large as the inside diameter of the neck of the bulb.

With earlier methods of preparing cathoderay tubes, a glass press was iirst made to serve for hermetical sealing of the glass to the metal and for rigid assembly oi the metal wires with respect to each other. This press was manufactured in the form of a iiat press or a circular press or a button stem. In all cases, however, the press was made in one operation and was then cooled. For satisfactory further processing the press should not be materially heated another time in the region where the wires go through the glass. However, a second heating of the glass had to be made for sealing the neck to the stem, and consequently the press of whatever style had to be made with a rather long ange of some shape so as to allow sealing at the extremity of the iiange and yet provide heat insulation by length of path to prevent softening of the a1- ready-formed press around the wires. With this invention the sealing can be completed in a single heating operation.

By the present invention a very short press structure can be utilized which is as elcient as the button stem in this regard. Furthermore, with this method it is possible to provide much longer pant-leg beads for insulation purposes on the lead wires than is practical on a mold for making button stems.

Another advantage of this invention is that it makes it possible to utilize a very large exhaust tubulation on the tube, allowing more rapid pumping than is possible where a small exhaust tubulation is necessary because ci the need tor (Cl. Z50- 141) makingl the wire lead circle small as is the case with the button stem.

'I'he invention will be understood from the iollowing description in connection with the accompanying drawings, in which: A

Fig, 1 is a, vertical section, partly broken away, showing an illustrative embodiment of the invention;

`Figs. 2 and 3 are sections through beads on wires for use in the invention Fig. 4 is a plan view along the line 4-4 of Fig. 1;

Figs. 5, 6 and 7 are sectional views partly broken away showing steps in the process;

y Fig. 8 is a section along the line 8 8 of Fig. 6; Fig. 9 is a section along the line 8-9 of Fig. 7; Fig. 10 is a vertical section through the lower part of the tube, showing the base attached;

Fig. 11 is a section along the line II-II of Fig. 10;

Fig. 12 is a section along the line I2-i2 of Fig. 11; L l,

Fig. 13 is a vertical section showing a modification of the invention; and

Fig. 14 is a vertical section showing another modiilcation.

In the drawings, reference character l indicates the neck portion of a cathode-ray tube with the remainder of the tube broken away. A cylindrically shaped mandrel or support 2 which is a portion of a sealing machine extends into the lower end of the neck I during the processing -of the tube. The mandrel 2 has a large opening 3 along its center, and several smaller openings 4 near its periphery through which wires can be inserted. These openings 4 are outside or the conically shaped extension l at the upper end.

A glass tube 6 having a ange I resting upon the conical extension 5 is supported by this mandrel. 'This tube B is the exhaust tubulation for the iinal cathoderay tube.

In order to increase the strength of the structure it is sometimes desirable to bring out the flange 1 on the eghaust tube 6 at some other angle than the right angle shown in Fig. l.

In preparing a beaded wire, a short glass cylinder lo is placed on a wire Il (Fig. 2) and this glass cylinder is drawn into a bead by heat and sealed to the wire Il, as shown at ill' (Fig. 3).

A supporting member I2 (Figs. l and 4)` of mica or other insulating material is provided with holes i3 near its periphery. These holes are provided with eyelets i4 through which the wires Il pass and to which these wires may be welded.

As shown in Fig. 4, it has been iound desirable to ,manufacture these cathode-ray tubes with which are resilient so as to hold the assembly l rigid in the neck by having the ends thereof pressing against the inside wallof the neck.

It is sometimes desirable to put additional centering spacers like those shown at I1 on the insulating support member I2 for purposes of holding the gun structure in the center of the tube.

The gun structure, consisting of deflection plates I8 and I9, cathode 20, first and second anodes 2l and 22, and control grid 23, is supported on ceramic rods 24, which are in turn supported upon wires which may be welded to some of the wires II which are attached to the supporting member I2 and pass through the beads I0. Lead wires 26 are connected from wires I I to different parts of the gun structure in the known manner. v

In carrying out the process one or more blow torches 28 are provided for heating the outside of the neck I in proximity to the beads I0' with the parts assembled as shown in Fig. 1, which also shows a general arrangement of the gun assembly,` the lead wires, the exhaust tubulation on its supporting mandrel, and the neck of the tube, ready for its sealing operation. 1 A portion of the side of Fig. 1 is shown ln Fig. 5 after the heating for sealing purposes has continued suiilciently to cause a shrinking-in of the glass of the neck I into a circular groove, as indicated at 29. In practicing the invention a number of stationary heaters 28 arranged in a circle apply heat all around the neck I, and the entire structure may be rotating to assure uniformity of heating of the glass. This heating process is shown carried farther in Fig. 6 where the glass has become still more molten under the llames, and the weight of the enlarged lower portion or cullet I' of the neck has caused the glass to pull away. This bottom undesired portion of the glass neck is discarded. Up to this point the flames have heated the beads l0' by transfer of heat through the glass, but upon removal of the neck portion I' the names impinge directly upon the beads I0' as will be obvious from Fig. 6 and upon the edge of the ange 'I of the tubulation 6 so as to seal the remaining lower end of the neck I to the beads I0 and to the outer edge of the ange 1 of the tubulation 6, as shown more clearly in Figs. 7 and 9. The dotted lines 30 in Fig. '1 and the indentations 3l in Fig. 9 show that the glass will tend to shrink-in still more between the positions of the beads I0 than at the points where the neck is sealed directly to these beads.

As shown in Fig. 8, the lead wires I I with their beads I0' are located on a circle and the wires I I contact only with the beads I0', while the neck I of the tube touches these beads only after this neck has been drawn inward by the action of the llames from the torches 28.

After the tube has been sealed as described above, the exhaust tubulation 6 may be attached to a vacuum system and the tube pumped out to create the desired vacuum in the usual way. When the tube has been processed on the pumps or a suilcient vacuum has been reached, the tube is removed by sealing on the tubulation 6 by heating to yield a result shown at the seal-of! tip 34 of Fig. 10. Fig. 10 also shows the tube base 35 attached to this finished cathode-ray tube, and the lead wires II terminating in the base pins or terminals 42.

The portion 36 of the base 35 is an annular ring extending up around the seal-oir tubulation 6,'and the portion 31 with the closed end 31' is a projection to fit an opening at the center of a tube socket. It is provided with a key 38 to enable the base to be inserted and oriented in the socket. The portion 3l also serves as a protecting housing for the sealed-cil tabulation 34. Baille'ns or plates 40 (Figs. 10-12) extend from the annular ring 36 to the wall 35' of the base and provide additional insulation between the leads I0, as will be obvious from Figs. 10, 11 and 12. The lower portions of the beads ID are made into a long pant-leg, so that the free path through air from the metal of one wire to the metal of the adjacent wire is considerably lengthened since the upper edges of the baille fins 40 extend considerably beyond the lower ends of the extended beads I0 (Fig. 12). The insulation with this type of glass work and base is further improved over old styles of button stems because thissealing method allows a very large radius for the circle of the lead wires as they come through the glass, so that these wires are located correspondingly farther apart. The holes 4I, (Figs. l0 and 12) provide for insertion of the contact pins 42, which may be either stamped into place or molded in place in the manufacture o1 the base.

In the modification shown in Fig. 13 the sealing method for attaching the neck 45 to the lead wires and the ange 1 is somewhat different from that already described. In this ligure the neck 45 is cut ofI and does not have the enlarged cullet portion shown in Fig. 1. An additional movable sleeve 46 of iron, carbon, or other nre-resistant material is provided with an inwardly sloping portion 4l at its top. The iires 28 play at an angle to the neck 45 so as to heat the bottom of this neck, and also to impinge directly upon the beads I0' and the rim oi' the flange l. When the lower portion or the neck 45 has become molten, the bulb of the tube is lowered so that the end ci the molten neck 45 strikes the sloping surface 41 oi this shaping mold 46, causing the molten glass to be forced inwardly against the partly molten beads l0 and partly molten rim of the ange l. This forced action assists in causing good fusing together oi' the glass elements. Subsequent lowering of the mold 46 permits further application of the fiame's to complete the sealing process. Aftersealing the neck and the ange together with the lead wires to form a hermetical joint, the tube is cooled by a slow annealing process and exhausted and sealed as already described.

Instead of lowering the bulb, as described above, it is sometimes desirable to employ the conventional method oi having a plurality of movable jaws, either two or four. which can be brought up against the molten glass to press it into shape and position instead of depending upon the shrinking of the glass during the heating, or depending upon the use of the sloping portion 41.

With the Jaw action, it will, of course, be desirable to have the neck cut so as to extend farther down than shown in Fig. 13.

The modification shown in Fig. 14 is particularly applicable to soft glass working. Here it is not necessary to go through the preliminary step of placing glass beads on the wires Il. The en" tire process of sealing the wires through the glass and attaching the exhaust tube tothe neck is done in one operation, thus providing the further advantage of getting a still greater increase in possible diameter of the circle for the lead wires il. The neck 52 may be straight, as shown, although it may be provided with a cullet similar to the one shown on the neck I of Fig. 1. In this modification the ange 'I' on the exhaust tubulation 6 has a wider flange, since it is possible to bring out the lead wires Il on a larger diameter circle. The flames from the blow torches impinge upon the outside of the neck 52, causing the glass to shrink-in and fuse with the rim of the flange 1', at the same time hermetically sealing the lead wires-II in place. The excess portion of the neck 52 drops away at the bottom in a manner indicated by the dotted lines 53. In this modification, using no beads on the Wires, the neck can also be cut oil, as shown in Fig. 13, and the sealing operation can be completed without requiring certain of the bottom portions of the neck to fall away.

In carrying out the process the conventional method of rotating the entire assembly onva machine using severa1 consecutive sets of iires or torches may be employed, thus rendering it easy to get different angles of ilrlng, as suggested in connection with Fig. 13.

For operations using soft glassv it is sometimes desirable to seal the terminals to the exhaust tubulations and the neck without using the preliminary step of placing beads on the glass, but for hard glass the beading has been found desirable as a preliminary step in obtaining the best hermetical sealing. 'Ihis present method of obtaining a very short mount structure is applicable to both hard and soft glass; whereas, heretoforeit has been practically impossible to manufacfture a button stem with its necessarily short mount structure when usingl hard glass.

While-this invention has been described in detail in connection with cathode-ray tubes, it is also applicable to vacuum tubes in general. The increased voltage insulation and the simplified glass working process are very valuable in the manufacture of many other types ofyacuum tubes.,

What is claimed is:

1. In the process or producing a cathode-ray tube, the step which comprises assembling an exhaust tubulation and neck of a tube with respect to each other in spaced relation with electric conductors in the openspace between them while supporting the gun structure of said tube in said neck on said conductors.

2. In the process of producing a cathode-ray tube, the step which comprises assembling an.

exhaust tubulation and neck of a tube with respect to each other in spaced relation with electric conductors in the open space between them while supporting the gun structure ofy said tube in said neck on said conductors, said conductors having glass beads thereon. y

3. In the process of producing .a cathode-ray tube, the step which. comprises assembling an exhaust 'tubulation and neck ci a tube with rem spect to each other in spaced reiatcn. with elec1 tric conductors in the open space between them while supporting the gun structure of said tube in said neck on said conductors, said conductors having glass beads thereon and hermetically sealed thereto.

4. In the process of producing a cathode-ray tube, the steps which comprise assembling an exhaust tubulation and neckvof a tube with respect to each other in spaced relation with electric conductors in the open space between them while supporting the gun structureof said tube in said neck on said conductors, and sealing said tubulation to said neck.

5. In the process of producing a cathode-ray tube, the step which comprises assembling an haust tubulation and neck of a tube with respect to each other in spaced relation with electric conductors in the open space between them while supporting the gun structure of said tube in said neck on said conductors, said tubulation comprising a tube with its end flared outwardly to form a rim.

6. In the process of producing a cathode-ray tube, the steps which comprise assembling an exhaust tubulation and neck of a tube with respect to each other in spaced relation with electric conductors in the open space between them while supporting the gun structure of said tube in said neck on said conductors, and applying heat to seal said tubulation to said neck.

'7. In the process of producing a cathode-ray tube, the steps which comprise assembling an exhaust tubulation and neck of a tube with rei spect to each other in spaced relation with electric conductors in the open space between them while supporting the gun structure of said tube in said neck on said conductors, applying heat to seal said tubulation to said neck, and simultaneously sealing said conductors in place.

8. The process which comprises assembling the internal metal elements of a cathode-ray tube to the electrical conductors thereof which are to lead through the glass for supporting said metal elements, and subsequently hermetically sealing said conductors and securing them with respect to one another simultaneous with the sealing of the bulb to the exhaust tubulation ready for exhaust.

9. A cathode-ray tube having electric conductors for said tube sealed in said tube in close proximity to the inside wall of the neck of said tube supporting the gun structure of said tube in said neck and having glass integral with the tube extending along said conductors outside of said tube, the distance between centers of conductors opposite each other being at least approximately three-quarters of the inside diameter of said neck.

10. A cathode-ray tube having electrical conductors sealed through the end of its neck portion and means to provide a meandering air path between exposed portions of adjacent conductors outside of said end.

i1. A cathode-ray tube having electrical conductors sealed through the end of its neck por.. tion and insulating baffles between exposed porF tions or said conductors outside of said tube.

l2. A cathode-ray tube having electrical conductors sealed through the end oi its neck portion and means ccrnprising battles and insulators on said conductors to provide a meandering air path between exposed, portions ci? adjacent con. aviators outside oi said end.. 

